Orthodontic appliance



FIG. 1 is a top right rear perspective view of an orthodontic appliance showing my new design;

FIG. 2 is a top right front perspective view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a front elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a right side elevation view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The dashed broken lines illustrate portions of the orthodontic appliance that form no part of the claimed design. 

CLAIM The ornamental design for an orthodontic appliance, as shown and described. 